390 



The beds of this Zone consist nearly everywhere of hard 

 limestones ; and the author gave his Zones the name of Pecten 

 cequivalvis on the score of utiHty only, because of its wide range 

 into other countries, and as it is a well-known fossil, generally 

 well preserved and conspicuous. 



The Spinatus deposits are to be studied in the Department of 

 the Moselle, of the Meurthe, in the neighbourhood of Gunders- 

 hofen on the lower Rhine, and in the Department of the Cote- 

 d'Or, for which consult Dr. Weight's valuable paper. They are 

 also to be seen at Lozere, at Abeyron, and other localities, and 

 are bibliographically dealt with in M. D'Archiac's Formations 

 Jurassique, vols. VI and VII, in his Hist, des Prog, de Geologie, 

 Paris, 1856. 



We now approach geographically the frontiers of this part of 

 Europe, and would observe that even a cursory examination of 

 the mutilated and obscured sei'ies of the Pranconian and 

 Suabian Lias, would much exceed our limits. This imperfection 

 of the geological record, is a consequence of its position in 

 regard to the region of the Alps, where incessant perturbations 

 contemporaneous with the deposits of the period, told upon 

 them in a most eflScacious manner to disturb their unity, and 

 disarrange that more perfect order which exists in our 

 undisturbed typical English Lias. So, deferring our remarks 

 upon the Lias of the Pranconian and Suabian Jui'a, we now 

 glance at the results won for us by the chief German workers in 

 the field of Liassic geology. 



The honourable labours of Quenstedt and Oppel have been 

 so many years before the world of Science — in the one case the 

 valuable palaeontology; in the other, the exact terminology 

 based upon a wide induction of particulars; the one a rich 

 storehouse of facts ; the latter assimilated and applied by the 

 leaders amongst the geologists of Europe — that we assume their 

 works are sufficiently familiar to need little more than a simple 

 reference. We would only for convenient comparison cite from 

 the Juraformation of Dr. Oppel, this an*angement for Wurtem- 

 berg and Northern Franconia (Bavaria). 



